// CHECKSTYLE_OFF: Copyrighted to the Android Open Source Project.
/*
 *  Licensed to the Apache Software Foundation (ASF) under one or more
 *  contributor license agreements.  See the NOTICE file distributed with
 *  this work for additional information regarding copyright ownership.
 *  The ASF licenses this file to You under the Apache License, Version 2.0
 *  (the "License"); you may not use this file except in compliance with
 *  the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */
// CHECKSTYLE_ON

package java.io;

/**
 * Wraps an existing {@link OutputStream} and performs some transformation on the output data while
 * it is being written. Transformations can be anything from a simple byte-wise filtering output
 * data to an on-the-fly compression or decompression of the underlying stream. Output streams that
 * wrap another output stream and provide some additional functionality on top of it usually inherit
 * from this class.
 *
 * @see FilterOutputStream
 */
public class FilterOutputStream extends OutputStream {

  /** The target output stream for this filter stream. */
  protected OutputStream out;

  /**
   * Constructs a new {@code FilterOutputStream} with {@code out} as its target stream.
   *
   * @param out the target stream that this stream writes to.
   */
  public FilterOutputStream(OutputStream out) {
    this.out = out;
  }

  /**
   * Closes this stream. This implementation closes the target stream.
   *
   * @throws IOException if an error occurs attempting to close this stream.
   */
  @Override
  public void close() throws IOException {
    Throwable thrown = null;
    try {
      flush();
    } catch (Throwable e) {
      thrown = e;
    }

    try {
      out.close();
    } catch (Throwable e) {
      if (thrown == null) {
        thrown = e;
      }
    }

    if (thrown != null) {
      throw new IOException(thrown);
    }
  }

  /**
   * Ensures that all pending data is sent out to the target stream. This implementation flushes the
   * target stream.
   *
   * @throws IOException if an error occurs attempting to flush this stream.
   */
  @Override
  public void flush() throws IOException {
    out.flush();
  }

  /**
   * Writes {@code count} bytes from the byte array {@code buffer} starting at {@code offset} to the
   * target stream.
   *
   * @param buffer the buffer to write.
   * @param offset the index of the first byte in {@code buffer} to write.
   * @param length the number of bytes in {@code buffer} to write.
   * @throws IndexOutOfBoundsException if {@code offset < 0} or {@code count < 0}, or if {@code
   *     offset + count} is bigger than the length of {@code buffer}.
   * @throws IOException if an I/O error occurs while writing to this stream.
   */
  @Override
  public void write(byte[] buffer, int offset, int length) throws IOException {
    IOUtils.checkOffsetAndCount(buffer, offset, length);
    for (int i = 0; i < length; i++) {
      // Call write() instead of out.write() since subclasses could
      // override the write() method.
      write(buffer[offset + i]);
    }
  }

  /**
   * Writes one byte to the target stream. Only the low order byte of the integer {@code oneByte} is
   * written.
   *
   * @param oneByte the byte to be written.
   * @throws IOException if an I/O error occurs while writing to this stream.
   */
  @Override
  public void write(int oneByte) throws IOException {
    out.write(oneByte);
  }
}
